Jay Pique wrote:
wrote:

snip
The Plot Thickens:
A Chief Warrant Officer (a surveyor by trade) told this crew, who
was
putting in a steel rebar mat, that only every third joint be tied
together. This raised some discussion among members of the crew,
one
of which swore that OSHA required that every joint be tied. This,
to
me, sounds like a dumb-ass thing to say. ANSI maybe, but not OSHA.
Further, he swore that the joints could not be welded, as the
welding
process weakens the steel. Also completely ridiculous as far as I
can
tell, in the context of the concrete system.

I told him (my buddy) that local building codes vary (and are all
subject to the building inspector) but the only reason rebar gets
tied
or welded together in a concrete system is to hold it in place until
the 'crete gets poured over it. 8 hours after the pour, that little
piece of wire has done its job. I further told him that perhaps
welding rebar may weaken the steel at that point, but does not have
a
significant effect on the overall strength of the concrete system.
snip

I've been pouring slabs on a rate job lately, and we only tie (most)
corners and where the rebar sags too much. Given the relatively
light
gauge of tie-wire I typically see used, and the relative lack of
tightening thereof, I doubt that the ties make any structural
difference.

Were it a slab of my own, I'd tie each joint - and well.

I agree. Unless of course it were what amounts to a driveway
(light-duty occasional use) with a mat of #8 rebar 2 inches above the
bottom of the slab and a mat of #5 rebar 4 inches above that--did I
mention a 15-inch overall thickness of the slab? As you can see, this
is slightly overengineered. Interstate highway specs on a (literally)
paved Border Patrol truck path.

As far as welding goes, I highly doubt a welded joint is anything
less
than multiply stronger than the tie-wired joints. YMMV.

JP

I also agree there. I think the point of the statement was that the
actual weld weakens the reinforcing rod at the joint because the heat
hardens the steel and makes it brittle (?). I'm not sure of the
(twisted) logic behind that statement.